Recently, Patent Foramen Ovale (hereinafter, abbreviated to PFO) has been identified as a cardiogenic factor responsible for stroke and migraine. PFO is a symptom caused when the foramen ovale, which causes right-to-left cardiac shunt in infancy, remains in the body even after the infant has grown up. It is reported that 20% to 30% of adults suffer from PFO.
The foramen ovale is formed in the Septum Secundum (hereinafter, described as “atrial septum secundum”) of the heart. Ordinarily, since the left atrial pressure is higher than the right atrial pressure in the heart, the left atrium is closed by the Septum Primum (hereinafter, described as a “foramen ovale valve”). However, when the right atrial pressure becomes higher than the left atrial pressure due to tension (for example, coughing or firmly maintaining posture) or the like, the foramen ovale opens toward the left atrium, whereby the blood flows into the left atrial side (arterial side) from the right atrial side (venous side). If the blood contains thrombi, the thrombi move to the arterial side from the venous side. The thrombi then move to the left atrium, the left ventricle, the aorta, and the brain in this order and become a factor responsible for stroke, migraine, and the like.
If percutaneous catheterization, which is conducted as a procedure for addressing the aforementioned disease, can produce the same effects as produced by open-heart surgery, this procedure is regarded as a desirable method.
Devices for closing surgery using percutaneous catheters can also be used for closing defects such as congenital atrial septal defect (ASD), PFO, ventricular septal defect (VSD), and patent ductus arteriosus (PDA). However, the devices used in the conventional procedure clamp the foramen ovale and the atrial septum secundum by using a disk-like membrane or an anchoring member for closing the defects and are allowed to indwell the body.
The body considers the membrane or anchoring member a foreign substance, and thrombi easily adhere thereto. Particularly, after adhering to the disk-like membrane of the left atrial side, the thrombi may move and cause a stroke and may break the thin foramen ovale. Moreover, the position of these members may not be fixed in a state of clamping the defect, and the members may stray from their position.
Accordingly, recently, a PFO closure device which sandwiches the foramen ovale and the atrial septum secundum between a pair of electrodes and applies electric energy from both the electrodes to connect tissues has been proposed. An example is disclosed in Japanese Application Publication No. 2009-233020. With this PFO closure device, biological tissue is held by a positioning member that protrudes from a catheter, a sticking member consisting of the pair of electrodes and a sandwiching member are then used to stick the sticking member into the foramen ovale valve, the foramen ovale valve and the atrial septum secundum are then sandwiched between the sticking member and the sandwiching member, and electric energy is applied to the biological tissue to connect the tissues. If such a device having the simple constitution as above is used, it is possible to reliably connect the foramen ovale to the atrial septum secundum by a simple procedure without causing a foreign substance to indwell the body.
Moreover, the device has a structure in which the positioning member, the sandwiching member, and the sticking member are individually operated at the operator's side of the device.
The aforementioned PFO closure device has a structure in which the positioning member, the sandwiching member, and the sticking member are individually operated at the operator's side of the device. Accordingly, the operation thereof is complicated.